1. Field of the Invention
The present invention relates to a portable cellular phone terminal, device and a portable cellular phone system that incorporates the same.
The present application claims priority of Japanese Patent Application No. 2004-261912 filed on Sep. 9, 2004, which is hereby incorporated by reference.
2. Description of the Related Art
Recently, a portable cellular phone terminal device has been provided with expensive accessory functions such as a camera or a TV tuner. For example, a camera performance of a camera-attached portable cellular phone terminal device has improved remarkably, so as to almost equal to that of an ordinary digital camera. Further, ease-of-use of the other functions has also improved, so that the accessory functions of the portable cellular phone terminal device other than communication functions are highly evaluated in utilization (Japanese Patent application Laid-open No. 2002-163555).
Conventionally, cellular phone service providers have employed an approach to increase contracted subscribers by providing a portable cellular phone terminal device less expensive than its net production cost. After selling the inexpensive portable cellular phone terminal device to the subscribers, the cellular phone service providers expect to collect a difference by charging for utilization of the portable cellular phone terminal device or a like. However, if the user buys the portable cellular phone terminal device from the cellular phone service provider and immediately cancels a contract of cellular phone services in order to utilize accessory functions of the portable cellular phone terminal device, the cellular phone service provider cannot collect a difference due to the inexpensive selling of the portable cellular phone terminal device. Conventionally, even if the subscriber who bought the portable cellular phone terminal device inexpensively has cancelled the contract of the cellular phone services, he can still have the portable cellular phone terminal device and use its accessory functions.
As described above, as the accessory functions of the portable cellular phone terminal device are improved, it has been concerned that more and more users would buy the portable cellular phone terminal device from the cellular phone service provider and immediately cancel the contract in order to utilize the accessory functions. Therefore, there is a need for such a system as to suppress such users from increasing.
It is to be noted that recently the portable cellular phone terminal device has been used more widely which uses an IC card such as an SIM card or a USIM card that stores information including a phone number of the user and information of the cellular phone service provider with which he is under contract. With such the portable cellular phone terminal device, by replacing the SIM card or a like, it is possible to use the same phone number among a plurality of portable cellular phone terminal devices. It is also possible to use the same portable cellular phone terminal device among a plurality of phone numbers.
It is necessary to allow for such the portable cellular phone terminal device using an SIM card when designing the system that suppresses an increase in number of the users who would like to temporarily contract for cellular phone services and buy the portable cellular phone terminal device inexpensively in order to utilize its accessory functions as described above.